Compressor Having Counterweight

ABSTRACT

A compressor may include a compression mechanism, a motor, and a counterweight assembly. The motor assembly is drivingly engaged to the compression mechanism and includes a rotor driving a driveshaft. The rotor drives the driveshaft. The counterweight assembly is mounted axially onto the driveshaft of the motor assembly and has a first laminated stack of plates that includes a plurality of first plates and a plurality of second plates. Each first plate defines a first polygonal-shaped aperture that has a plurality of sides. Each second plate defines a second polygonal-shaped aperture that has a plurality of second sides. The first sides of the first polygonal-shaped apertures are rotationally misaligned with the second sides of the second polygonal-shaped apertures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/588,953, filed on Nov. 21, 2017. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to a compressor having a counterweight.

BACKGROUND

This section provides background information related to the present disclosure and is not necessarily prior art.

A compressor may include counterweights press fitted axially onto a driveshaft of a motor assembly to facilitate balancing of the motor assembly. Press-fitting conventional counterweights onto the driveshaft requires time consuming and expensive machining of the inner bore of the counterweights and the driveshaft, and requires considerable assembly force. The present disclosure provides counterweights that do not require tight tolerance machining of the inner bore and the driveshaft. The counterweights of the present disclosure also reduce the assembly force needed to press fit the counterweights onto the driveshaft while providing increased retention of the counterweights onto the driveshaft.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

In one form, a compressor includes a compression mechanism, a motor, and a counterweight assembly. The motor assembly is drivingly engaged to the compression mechanism and includes a rotor driving a driveshaft. The rotor drives the driveshaft. The counterweight assembly is mounted axially onto the driveshaft of the motor assembly and has a first laminated stack of plates that includes a plurality of first plates and a plurality of second plates. Each first plate defines a first polygonal-shaped aperture that has a plurality of sides. Each second plate defines a second polygonal-shaped aperture that has a plurality of second sides. The first sides of the first polygonal-shaped apertures are rotationally misaligned with the second sides of the second polygonal-shaped apertures.

In some configurations, the first and second plates are attached to each other by fasteners.

In some configurations, each of the first plates is disposed directly adjacent to at least one of the second plates.

In some configurations, the counterweight assembly includes a unitary counterweight attached to the first laminated stack of plates.

In some configurations, the unitary counterweight is formed from a different material than the first and second plates.

In some configurations, the counterweight assembly includes a second laminated stack of plates mounted axially onto the driveshaft and attached to the first laminated stack of plates. A U-shaped recess is formed in the second laminated stack of plates.

In some configurations, a solid body is contained in the U-shaped recess formed in the second laminated stack of plates.

In some configurations, the solid body is made up of a different material than the first and second laminated stack of plates.

In some configurations, the counterweight assembly includes a second U-shaped laminated stack of plates attached to the first laminated stack of plates.

In some configurations, a recess is formed in the second U-shaped laminated stack of plates.

In some configurations, the first laminated stack of plates are attached to the rotor.

In some configurations, the counterweight assembly includes a laminated stack of rings attached to the first laminated stack of plates.

In another form, a compressor includes a compression mechanism, a motor assembly, and first and second counterweight assemblies. The motor assembly is drivingly engaged to the compression mechanism. The motor assembly includes a rotor and a driveshaft. The rotor drives the driveshaft. The first and second counterweight assemblies are mounted axially onto the driveshaft with the rotor disposed therebetween. Each of the first and second counterweight assemblies has a first laminated stack of plates that includes a plurality of first plates and a plurality of second plates. Each first plate defines a first polygonal-shaped aperture that has a plurality of first sides. Each second plate defines a second polygonal-shaped aperture that has a plurality of second sides. The first sides of the first polygonal-shaped apertures are rotationally misaligned with the second sides of the second polygonal-shaped apertures.

In some configurations, edges of the first plates are misaligned with edges of the second plates.

In some configurations, edges of the first plates are aligned with edges of the second plates.

In some configurations, the first counterweight assembly and the second counterweight assembly are attached to the rotor.

In some configurations, the first counterweight assembly includes a laminated stack of rings attached to the first laminated stack of plates.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a cross-sectional view of a compressor having first and second counterweight assemblies according to the principles of the present disclosure;

FIG. 2 is an exploded view of one of the counterweight assemblies shown in FIG. 1;

FIG. 3 is a perspective view of the counterweight assembly shown in FIG. 2;

FIG. 4 is a cross-sectional view of the counterweight assembly of Figure of 3 taken along line 4-4 of FIG. 3;

FIG. 5 is an exploded view of another counterweight assembly having a plurality of first and second plates staggered relative to each other at an angle;

FIG. 6 is a top view of the counterweight assembly shown in FIG. 5;

FIG. 7 is a perspective view of a motor assembly of the compressor shown in FIG. 1 with the first and second counterweight assemblies attached thereto;

FIG. 8 is a perspective view of another one of the laminated counterweight assemblies shown in FIG. 1;

FIG. 9 is a perspective view of another motor assembly with first and second counterweight assemblies attached thereto;

FIG. 10 is a perspective view of another counterweight assembly;

FIG. 11 is a perspective view of yet another counterweight assembly;

FIG. 12 is a perspective view of the counterweight assembly of FIG. 11 with a cover attached thereto;

FIG. 13 is an exploded view of yet another counterweight assembly; and

FIG. 14 is a perspective view of another motor assembly with the counterweight assemblies of FIG. 13 attached thereto.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

The principles of the preset disclosure are suitable for incorporation in many different types of scroll and rotary compressors, including hermetic machines, open drive machines and non-hermetic machines. For exemplary purposes, a compressor 10 is shown as a hermetic scroll refrigerant-compressor of the low-side type (i.e., where the motor and at least a portion of the compression mechanism are disposed in a section-pressure region of the compressor) as illustrated in FIG. 1. It will be appreciated that the principles of the present disclosure are also applicable to high-side compressors (i.e., compressors having the motor and compression mechanism disposed in a discharge-pressure region of the compressor).

With reference to FIG. 1, a compressor 10 is provided that may include a hermetic shell assembly 12, a bearing housing assembly 14, a motor assembly 16, a compression mechanism 18, a seal assembly 20, a first counterweight assembly 22 a and a second counterweight assembly 22 b. The shell assembly 12 may house the bearing housing assembly 14, the motor assembly 16, the compression mechanism 18, the seal assembly 20, and the first and second counterweight assemblies 22 a, 22 b.

The shell assembly 12 may generally form a compressor housing and may include a cylindrical shell 26, an end cap 28 at the upper end thereof, a transversely extending partition 30, and a base 32 at a lower end thereof. The end cap 28 and the partition 30 may generally define a discharge chamber 34. A suction gas inlet fitting 38 may be attached to the shell assembly 12 at another opening and may communicate with a suction chamber 40 defined by the shell 26 and the partition 30. The partition 30 may include a discharge passage 42 therethrough providing communication between the compression mechanism 18 and the discharge chamber 34.

The bearing housing assembly 14 may be affixed to the shell and may include a main bearing housing 44 and a bearing 46. The main bearing housing 44 may house the bearing 46 therein and may define an annular flat thrust bearing surface 48 on an axial end surface thereof.

The motor assembly 16 may include a motor stator 50, a rotor 52, and a driveshaft 54. The motor stator 50 may be press fit into the shell 12. The driveshaft 54 may be rotatably driven by the rotor 52 and may be rotatably supported within the bearing 46. The rotor 52 may be press fit on the driveshaft 54. The driveshaft 54 may include an eccentric crankpin 56.

The compression mechanism 18 may generally include an orbiting scroll 58 and a non-orbiting scroll 60. The orbiting scroll 58 may include an end plate 62 having a spiral wrap 64 on the upper surface thereof and an annular flat thrust surface 66 on the lower surface. The thrust surface 66 may interface with the annular flat thrust bearing surface 48 on the main bearing housing 44. A cylindrical hub 68 may project downwardly from the thrust surface 66 and may have a drive bushing 70 rotatably disposed therein. The drive bushing 70 may include an inner bore in which the crankpin 56 is drivingly disposed. A flat surface of the crankpin 72 may drivingly engage a flat surface in a portion of the inner bore of the drive bushing 70 to provide a radially compliant driving arrangement.

The non-orbiting scroll 60 may include an end plate 74 and a spiral wrap 76 projecting downwardly from the end plate 74. The spiral wrap 76 may meshingly engage the spiral wrap 64 of the orbiting scroll 58, thereby creating a series of moving fluid pockets. The fluid pockets defined by the spiral wraps 64, 76 may decrease in volume as they move from a radially outer position (at a section pressure) to a radially intermediate position (at an intermediate pressure) to a radially inner position (at a discharge pressure) throughout a compression cycle of the compression mechanism 18.

The end plate 74 may include an annular recess 82. The annular recess 82 may receive the seal assembly 20 and cooperate with the seal assembly 20 to define an axial biasing chamber 84 therebetween. The biasing chamber 84 is in communication with one of the series of moving compression pockets at an intermediate pressure via a passageway (not shown). Intermediate-pressure working fluid within the biasing chamber 84 may axially bias the non-orbiting scroll 60 towards the orbiting scroll 58.

As shown in FIGS. 2 and 3, the first counterweight assembly 22 a may include a laminated stack of plates 86 including a plurality of first and second plates 86 a, 86 b stacked in an alternating fashion. The first and second plates 86 a, 86 b may be attached to one another using fasteners 87 a (e.g., rivets, bolts, etc.). In other configurations, the first and second plates 86 a, 86 b could be attached to each other by interlocking members and/or welds instead of or in addition to the fasteners 87 a. The first and second plates 86 a, 86 b may be made out of a metallic material, for example, and may be formed by a stamping process, for example.

With continued reference to FIGS. 2 and 3, each of the first and second plates 86 a, 86 b may define a polygonal-shaped aperture 88 (FIG. 2) that together (i.e., when the plates 86 a, 86 b are attached to each other) forms a polygonal-shaped bore 90 (FIG. 3) in the first counterweight assembly 22 a. Although the polygonal-shaped aperture 88 in each plate 86 a, 86 b is shown in FIG. 2 as a nonagon (i.e., a nine-sided polygon), in some configurations, the polygonal-shaped aperture 88 may have more or less than nine sides 92.

As shown in FIG. 4, the sides 92 of the polygon-shaped aperture 88 of the first plates 86 a may be rotationally misaligned from the sides 92 of an adjacent second plate 86 b such that vertices 94 of the plates 86 a, 86 b form depressions 95 between the sides 92 of adjacent plates 86 a, 86 b. The rotational misalignment between the apertures 88 of the plates 86 a, 86 b may be accomplished by orienting the apertures 88 in the plates 86 a, 86 b relative to each other such that the vertices 94 of the first plates 86 a are angularly between (e.g., approximately halfway between) the vertices 94 of the second plates 86 b. In this way, edges 97 of the plates 86 a, 86 b are aligned to each other. In some configurations, the vertices 94 of the first plates 86 a may be approximately angularly aligned with midpoints of the sides 92 of the second plates 86 b. In some configurations, as shown in FIGS. 5 and 6, the rotational misalignment between the apertures 88 of the plates 86 a, 86 b may be accomplished by orienting the plates 86 a, 86 b relative to each other such that the vertices 94 of the first plates 86 a are angularly between (e.g., approximately halfway between) the vertices 94 of the second plates 86 b, or by staggering the first plates 86 a at an angle a relative to the adjacent second plate 86 b such that the edges 97 of the first plates 86 a and the adjacent second plate 86 b are misaligned (i.e., offset). The angle between the plates 86 a, 86 b in such configuration maybe 20 degrees, for example.

As shown in FIGS. 1 and 7, each counterweight assembly 22 a, 22 b may be press fitted onto the driveshaft 54 at opposite sides of the rotor 52. An axial position of each counterweight assembly 22 a, 22 b on the driveshaft 54 may be determined at least in part by a moment arm distance required to balance the forces acting on the motor assembly 16. Due to the relative material hardness between the plates 86 a, 86 b and the driveshaft 54 (i.e., the material of the plates 86 a, 86 b has a lower hardness than the material of the driveshaft 54), areas of the plates 86 a, 86 b at or near the apertures 88 may yield as the driveshaft 54 is pressed into the bore 90 of each counterweight assembly 22 a, 22 b. Material at or near midpoints of the sides 92 of the plates 86 a, 86 b may yield relatively easily since the material at the midpoints of the sides 92 of any given plate 86 a, 86 b is not supported by the material of the directly adjacent plates 86 a, 86 b (since the midpoint of each side 92 of a given plate 86 a, 86 b is rotationally aligned with the vertices 94 of the directly adjacent plates 86 a, 86 b ). The displaced material from the midpoints of the sides 92 of the plates 86 a, 86 b fill in the depressions 95. This process occurs at each plate 86 a, 86 b until the driveshaft 54 is fully inserted into each counterweight assembly 22 a, 22 b. Press fitting the driveshaft 54 into the bore 90 of each counterweight assembly 22 a, 22 b as described above reduces the force required to insert the driveshaft 54 into the bore 90. Additionally, this process improves retention of the counterweight assemblies 22 a, 22 b on the driveshaft 54 and without having to machine the apertures 88 to tight tolerances.

As shown in FIGS. 7 and 8, the second counterweight assembly 22 b may include a laminated stack of plates 96 and a U-shaped unitary counterweight 98. The laminated stack of plates 96 can be similar or identical to the laminated stack of plates 86 described above, and therefore, will not be described in detail.

The unitary counterweight 98 maybe attached to the laminated stack of plates 96 by fasteners 100 (e.g., rivets) to further adjust the mass and center of gravity of the second counterweight assembly 22 b, and to facilitate balancing of the rotor 52 and the driveshaft 54 of the motor assembly 16. While the configuration shown in FIG. 1 includes the unitary counterweight 98 attached to the second counterweight assembly 22 b, in some configurations, the unitary counterweight 98 may also be attached to the first counterweight assembly 22 a to achieve the intended benefit (i.e., balancing of the rotor 52 and the driveshaft 54). The unitary counterweight 98 may be made of the same or a different material than the laminated stack of plates 96. For example, in some configurations, the laminated stack of plates 96 and the unitary counterweight 98 may be made out of steel. In other configurations, the laminated stack of plates 96 may be made out of steel while the unitary counterweight 98 may be made out of brass.

With reference to FIG. 9, another rotor 220, first counterweight assembly 222 a, and second counterweight assembly 222 b are provided that may be incorporated into the compressor 10 instead of the rotor 52, the first counterweight assembly 22 a, and the second counterweight assembly 22 b. The first counterweight assembly 222 a may include a first laminated stack of plates 246 and the second counterweight assembly 222 b may include a second laminated stack of plates 248. The first and second laminated stack of plates 224, 226 can be similar or identical to the laminated stack of plates 86 described above. As shown in FIG. 9, each counterweight assembly 222 a, 222 b may be attached to opposing ends of the rotor 220 by fasteners 250 such that the rotor 220 and each counterweight assembly 222 a, 222 b may be press fit onto the driveshaft 54 as a single component.

With reference to FIG. 10, another counterweight assembly 322 a is provided that may be incorporated into the compressor 10 in the place of either one or both of the counterweight assemblies 22 a, 22 b. The counterweight assembly 322 a could include a first laminated stack of plates 324 (which may be similar or identical to the laminated stack of plates 86) and a second laminated stack of plates 326 attached to the first laminated stack of plates 324 by fasteners 328 (e.g., rivets or bolts).

The second laminated stack of plates 326 may include a plurality of first and second plates 326 a, 326 b. The plates 326 a, 326 b may be made out of a metallic material, for example, and may be formed by a stamping process, for example. The first and second plates 326 a, 326 b may be stacked in an alternating fashion similar to the laminated stack of plates 86 described above.

Each of the first and second plates 326 a, 326 b may define a polygonal-shaped aperture that together (i.e., when the plates 328a, 328b are attached to each other) forms a polygonal-shaped bore 330 in the laminated stack of plates 326. Although the polygonal-shaped aperture in each plate 326 a, 326 b is shown as a nonagon (i.e., a nine-sided polygon), in some configurations, the polygonal-shaped aperture may have more or less than nine sides 332. The sides 332 of the polygon-shaped aperture of the first plate 326 a may be rotationally misaligned from the sides 332 of an adjacent second plate 326 b in a similar manner as the sides 92 of the plates 86 a, 86 b described above.

Each of the first and second plates 326 a, 326 b may also define a U-shaped aperture that together (i.e., when the plates 326 a, 326 b are attached to each other) forms a U-shaped recess 334 in the laminated stack of plates 326. The recess 334 may adjust the mass and the center of gravity of the counterweight assembly 322 a. Although the recess 334 shown in FIG. 10 is U-shaped, the recess 334 may be various shapes such as circular, square, or rectangular, for example, to adjust the mass and the center of gravity of the counterweight assembly 322 a and meet balancing requirements.

With reference to FIG. 11, another counterweight assembly 422 a is provided that may be incorporated into the compressor 10 in the place of the counterweight assemblies 22 a, 22 b, 322 a. The counterweight assembly 422 a could include a first laminated stack of plates 424 (which may be similar or identical to the laminated stack of plates 86) and a second U-shaped laminated stack of plates 426 attached to the first laminated stack of plates 424 by fasteners 428 (e.g., rivets or bolts).

The second laminated stack of plates 426 may include a plurality of first and second plates 426 a, 426 b. The plates 426 a, 426 b may be made out of a metallic material, for example, and may be formed by a stamping process, for example. The first and second plates 426 a, 426 b may be stacked in an alternating fashion similar to the laminated stack of plates 86 described above.

Each of the first and second plates 426 a, 426 b may define a U-shaped aperture that together (i.e., when the plates 426 a, 426 b are attached to each other) forms a U-shaped recess 430 in the second laminated stack of plates 426. The recess 430 may adjust the mass and the center of gravity of the counterweight assembly 422 a. In some configurations, as shown in FIG. 12, a unitary body 432 may be received in the recess 430 formed in the second laminated stack of plates 426 to further adjust the mass and the center of gravity of the counterweight assembly 422 a. The unitary body 432 may be made of a material that is different from the material of the first and second laminated stack of plates 424, 426. For example, the unitary body may be made of brass while the first and second laminated stack plates 424, 426 may be made of steel. A cover plate 434 may be attached to the outermost first plate 426 a to retain and protect the unitary body 432 received in the recess 430.

With reference to FIGS. 13 and 14, another counterweight assembly 522 a is provided that may be incorporated into the compressor 10 in the place of the counterweight assemblies 22 a, 22 b, 322 a, 422 a. The counterweight assembly 522 a could include a laminated stack of plates 524 (which may be similar or identical to the laminated stack of plates 86) and a laminated stack of rings 526 attached to the laminated stack of plates 524 via welds, for example.

The laminated stack of rings 526 may include a plurality of first and second rings 526 a, 526 b. The first and second rings 526 a, 526 b may be made out of a metallic material, for example, and may be formed by a stamping process, for example. The first and second rings 526 a, 526 b may define polygon-shaped apertures 528 that are aligned with polygon-shaped apertures 530 of first and second plates 524 a, 524 b of the laminated stack of plates 524. The apertures 528 of the rings 526 a, 526 b may have sides that are rotationally misaligned in a similar manner as the sides 92 of the plates 86 a, 86 b described above. The first and second rings 526 a, 526 b may cooperate with the laminated stack of plates 524 to increase the engagement length between the counter weight assembly 522 a and the driveshaft 54. In this way, retention between the counterweight assembly 522 a and the driveshaft 54 is improved during operation of the compressor 10 while adding minimal mass to the driveshaft 54.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A compressor comprising: a compression mechanism; a motor assembly drivingly engaged to the compression mechanism, the motor assembly including a rotor and a driveshaft, the rotor driving the driveshaft; and a counterweight assembly mounted axially onto the driveshaft of the motor assembly, the counterweight assembly having a first laminated stack of plates including a plurality of first plates and a plurality of second plates, each first plate defining a first polygonal-shaped aperture having a plurality of first sides, each second plate defining a second polygonal-shaped aperture having a plurality of second sides, wherein the first sides of the first polygonal-shaped apertures are rotationally misaligned with the second sides of the second polygonal-shaped apertures.
 2. The compressor of claim 1, wherein the plurality of first and second plates are attached to each other by fasteners.
 3. The compressor of claim 1, wherein each of the first plates is disposed directly adjacent to at least one of the second plates.
 4. The compressor of claim 1, wherein the counterweight assembly includes a unitary counterweight attached to the first laminated stack of plates.
 5. The compressor of claim 4, wherein the unitary counterweight is formed from a different material than the plurality of first and second plates.
 6. The compressor of claim 1, wherein the counterweight assembly includes a second laminated stack of plates mounted axially onto the driveshaft and attached to the first laminated stack of plates, and wherein a U-shaped recess is formed in the second laminated stack of plates.
 7. The compressor of claim 6, wherein a solid body is contained in the U-shaped recess formed in the second laminated stack of plates.
 8. The compressor of claim 7, wherein the solid body is made up of a different material than the plurality of first and second plates.
 9. The compressor of claim 1, wherein the counterweight assembly includes a second U-shaped laminated stack of plates attached to the first laminated stack of plates.
 10. The compressor of claim 9, wherein a recess is formed in the second U-shaped laminated stack of plates.
 11. The compressor of claim 1, wherein the first laminated stack of plates are attached to the rotor.
 12. The compressor of claim 1, wherein the counterweight assembly includes a laminated stack of rings attached to the first laminated stack of plates.
 13. A compressor comprising: a compression mechanism; a motor assembly drivingly engaged to the compression mechanism, the motor assembly including a rotor and a driveshaft, the rotor driving the driveshaft; and first and second counterweight assemblies mounted axially onto the driveshaft with the rotor disposed therebetween, each of the first and second counterweight assemblies having a first laminated stack of plates including a plurality of first plates and a plurality of second plates, each first plate defining a first polygonal-shaped aperture having a plurality of first sides, each second plate defining a second polygonal-shaped aperture having a plurality of second sides, wherein the first sides of the first polygonal-shaped apertures are rotationally misaligned with the second sides of the second polygonal-shaped apertures.
 14. The compressor of claim 13, wherein edges of the first plates are misaligned with edges of the second plates.
 15. The compressor of claim 13, wherein edges of the first plates are aligned with edges of the second plates.
 16. The compressor of claim 13, wherein each of the first plates is disposed directly adjacent to at least one of the second plates.
 17. The compressor of claim 13, wherein the first counterweight assembly includes a unitary counterweight attached to the first laminated stack of plates.
 18. The compressor of claim 13, wherein the first counterweight assembly includes a second laminated stack of plates mounted axially onto the driveshaft and attached to the first laminated stack of plates, and wherein a U-shaped recess is formed in the second laminated stack of plates.
 19. The compressor of claim 18, wherein a solid body is contained in the U-shaped recess formed in the second laminated stack of plates, and wherein the solid body is made up of a different material than the plurality of first and second plates.
 20. The compressor of claim 13, wherein the first counterweight assembly includes a second U-shaped laminated stack of plates attached to the first laminated stack of plates, and wherein a U-shaped recess is formed in the second U-shaped laminated stack of plates.
 21. The compressor of claim 13, wherein the first counterweight assembly and the second counterweight assembly are attached to the rotor.
 22. The compressor of claim 13, wherein the first counterweight assembly includes a laminated stack of rings attached to the first laminated stack of plates. 